1. Field of the Invention
The present invention relates to a digital video signal processor, and more particularly, to a digital video signal processor such as a digital video tape recorder or a digital video camera for processing a black-and-white video signal. The present invention is based on Korean Application No. 96-21840, which is incorporated herein by reference.
2. Description of the Related Arts
In general, when video data is recorded on a video tape in a digital video cassette recorder or a digital camcorder, the video data is recorded in a predetermined format.
FIGS. 1A through 1C illustrate one of the recording formats of a general digital video cassette recorder.
FIG. 1A shows a discrete cosine transform (DCT) block which is a set of 8.times.8 (64) pixels. FIG. 1B shows a macro block having six DCT blocks, i.e., four luminance components Y1, Y2, Y3 and Y4, and two color difference components Cb and Cr. FIG. 1C shows a video segment which consists of five macro blocks MB1, MB2, MB3, MB4 and MB5. Each of the DCT blocks for the luminance components Y1, Y2, Y3 and Y4 of the macro block in FIG. 1B are discrete-cosine-transformed to be 14 bytes of DCT coefficients, which includes one DC coefficient and a plurality of AC coefficients. Also, each of the DCT blocks for the color difference components Cb and Cr are discrete-cosine-transformed to be 10 bytes of DCT coefficients, which includes one DC coefficient and a plurality of AC coefficients.
However, in the general digital video signal recorder, even when a user records a black-and-white video signal, the AC coefficients of the color difference components Cb and Cr are still recorded on the tape, which results in a lowering of the compression efficiency. Further, the AC coefficients of the color difference components Cb and Cr may vary without being kept at a predetermined level, which results in noise in the video signal.